Method for manufacturing an electrode arrangement for a battery cell

Abstract

The invention relates to an electrode arrangement for a battery cell, comprising a plurality of first electrodes (1) and a plurality of second electrodes (2) which are alternately stacked on top of each other in a stacking direction (s) or wound up to form an electrode roll (R) in the electrode arrangement and alternately follow one another in a radial direction (r), wherein the first electrodes (1) and the second electrodes (2) each have an electrically conductive carrier layer (3) and a coating (4) of an active material on at least one side of the carrier layer (3), and an edge section of each carrier layer (3) is designed as a contact section (5) which is at least partially free of the coating (4).To enable large-area contact between the first electrodes (1) and between the second electrodes (2), an electrically conductive material (6-1; 6-2) is introduced between the contact sections (5-1) of adjacent first electrodes (1) and between the contact sections (5-2) of adjacent second electrodes (2) to electrically connect the contact sections (5-1) of the first electrodes (1) to each other and the contact sections (5-2) of the second electrodes (2) to each other. This allows for large-area contact between the electrodes (1, 2) while avoiding excessively high current densities at the contact point.

Description

The invention relates to a method for producing an electrode arrangement for a battery cell according to the preamble of claim 1.A battery cell, such as a lithium battery cell, stores energy in the form of an electrochemical reaction in which cations, for example, form a lithium battery cell. Lithium ions move between positive and negative electrodes. The two electrodes are designated as anode (negative pole) and cathode (positive pole) according to their respective function during the discharge of the cell. The electrodes are protected from direct contact by a separator which is permeable to the cations (for example the lithium ions).Since the electrode materials do not have sufficient mechanical strength, they are each applied to a metal foil, the so-called collector foil, which serves for current conduction and contacting. Usually, a copper foil is used for the anode and an aluminum foil for the cathode.To produce a battery cell, the collector foils coated with the electrode materials are rolled together with the separators to form an electrode roll ("jelly roll"), or folded in a Z shape ("Z-following") or stacked to form an electrode stack ("stack"). This produces an electrode assembly (electrode stack) in which the largest possible area of the layer structure of the electrodes and the separators is achieved. The electrode arrangement can then be accommodated in a space-saving manner in a cell housing. For the purpose of current dissipation (during the discharge of the battery cell) or for the purpose of current supply (during the charging of the battery cell), an electrical contact to the collector foils has to be produced, via which electrical contact an electrical current can be conducted to the contact points arranged on the outer side of the cell housing.The following methods for contacting the electrodes of a battery cell are known from the prior art: a) The collector foil has an extension ("tab") at one or more locations, which extension is connected to further components, e.g. the outer contact surfaces of the battery, during the later assembly process of the battery cell. In this contacting method, the complete current, which flows through the cell during the charging or discharging process, flows through this extension(s), so that a concentration or a maximum of the current density occurs starting from this point. The extensions may be part of the collector foils themselves or separately applied components. b) An uncoated part of the metal foil protrudes at an edge of the rolled, folded or stacked electrode assembly across the entire width of the electrode across the edge of the rolled, folded or stacked foil. For contacting, the protruding edges of the electrode are bent over and welded to a contact plate, which is connected to further components, e.g. the outer contact surfaces of the battery, during the later assembly process of the battery cell ("tabless design").From DE 10 2022 103 728 B3 a battery cell is known having a housing, an electrode stack arrangement, at least one clamping arrangement and at least two counter elements assigned to the clamping arrangement, wherein the electrode stack arrangement is arranged in the housing and has first electrode arrangements and second electrode arrangements, wherein the first electrode arrangements have first electrodes and first strip elements and the second electrode arrangements have second electrodes and second strip elements and the at least one clamping arrangement has a base part, two clamping elements and at least two arms, which each extend between the base part and one of the clamping elements and are configured to apply a first force to the clamping elements in the direction of the assigned counter elements. First strip elements or second strip elements are arranged between at least one of the clamping elements and at least one of the counter elements, and the base part forms a connection element, which can be contacted from the outside, for electrically contacting the battery cell and is electrically connected to the first electrodes via the first strip elements or to the second electrodes via the second strip elements.A further battery cell and a method for producing the same are known from DE 10 2021 211 861 A1, wherein first electrode layers of the battery cell each have an electrically conductive first protrusion on a first side with respect to adjacent second electrode layers, wherein the first protrusions are embedded in a first electrical conductive medium and are electrically coupled to one another via the first electrical conductive medium. Correspondingly, second electrode layers of the battery cell can be embedded in a second electrical conducting medium on a second side opposite the first side.DE 10 2017 210 649 A1 describes a method for contacting an energy store which has at least one tab stack of contact tabs of electrodes arranged one above the other, wherein, in a step for producing an electrically conductive connection of the contact tabs, molten metal material is printed from a melt print head onto at least a partial region of an edge region of the tab stack.Proceeding from this background, the object of the invention is to provide an electrode arrangement, in particular in the form of an electrode stack or an electrode roller for a battery cell, which enables large-area contacting of the electrodes while avoiding excessively high current densities at the contact point. A further object is to provide a method for producing an electrode arrangement, wherein the number of steps required for contacting the electrodes of the electrode arrangement and / or the complexity of the contacting is to be minimized.These objects are achieved by the invention with the method for producing an electrode arrangement having the features of claim 1.The electrode arrangement for a battery cell produced according to the invention is in the form of an electrode stack or an electrode roll and can be used in particular in a lithium-ion battery cell. The electrode arrangement comprises a plurality of first electrodes and a plurality of second electrodes which, in the case of an electrode stack, are alternately stacked on one another in a stacking direction or wound around a roller axis in an electrode roller and are alternately successive in a radial direction (r), wherein the first electrodes and the second electrodes each have an electrically conductive carrier layer and a coating of an active material on at least one side of the carrier layer, and an edge section of each carrier layer is formed as a contact section which is at least partially free of the coating, wherein the contact sections of the first electrodes can expediently be electrically conductively connected to a first connection element and the contact sections of the second electrodes can expediently be electrically conductively connected to a second connection element. According to the invention, an electrically conductive material is respectively introduced between the contact sections of adjacent first electrodes in order to connect the contact sections of the first electrodes to one another in an electrically conductive manner. Accordingly, an electrically conductive material is likewise respectively introduced between the contact sections of adjacent second electrodes in order to connect the contact sections of the second electrodes to one another in an electrically conductive manner.The first electrodes are electrically conductively contacted to one another by the electrically conductive material introduced between the contact sections of adjacent first electrodes, and correspondingly the second electrodes are also electrically conductively contacted to one another by the electrically conductive material introduced between adjacent second electrodes. In this case, the portions of the first electrodes which are electrically contacted to one another via the electrically conductive material are expediently located on a first side of the electrode arrangement, and the portions of the second electrodes which are electrically contacted to one another via the electrically conductive material are located on a second side of the electrode arrangement which expediently lies opposite the first side. As a result, electrically conductive contact sections for the electrical contacting of the first electrodes are formed on the first side of the electrode arrangement and electrically conductive contact sections for the electrical contacting of the second electrodes are formed on the second side of the electrode arrangement, which contact sections can be connected to connection elements reliably and in a simple manner in order to ensure an electrical current flow with a homogeneous current density distribution via the connection elements and the contact sections.The first electrodes can be the anodes and the second electrodes can be the cathodes of the electrode arrangement, or vice versa.In the electrode arrangement produced according to the invention, an electrically insulating separator is preferably arranged in each case between an electrode of the plurality of first electrodes and a second electrode of the plurality of second electrodes adjacent thereto in the electrode stack. The electrical separators ensure that the first electrodes and the second electrodes do not have electrical contact with each other, thereby avoiding electrical shorts. The separators which are arranged between a first electrode and a second electrode expediently extend over the regions of the first and second electrodes which are provided with the coating of the active material. In the edge portions (contact portions) in which no coating of an active material is present on the support layer of the respective electrodes, the adjacent first and second electrodes are expediently spaced apart from each other, which ensures that the electrically conductive support layers of the first and second electrodes do not come into contact with each other.The carrier layer of the first electrodes and the carrier layer of the second electrodes can be formed from a different carrier material. For example, the first electrodes may comprise a carrier material made of a copper foil or a copper sheet and the carrier material of the carrier layer of the second electrodes may be an aluminum foil or an aluminum sheet.The electrically conductive material introduced between adjacent first electrodes can be the same material as the carrier material of the first or the second electrodes or a different material therefrom. The same applies to the electrically conductive material which is introduced between adjacent second electrodes.The electrically conductive material is preferably a plastically deformable material and in particular a material which is pasty or viscous at room temperature or at temperatures above room temperature. This makes it possible in the production method to apply the electrically conductive material first to a contact section of the carrier layer of a lower electrode, then to plastically deform it, for example by pressing with a roller or a die, and then to apply an upper electrode thereon, wherein in the edge sections (contact sections) of the electrodes free from the coating, the electrically conductive material is pressed against the lower electrode by the upper electrode. As a result of the plastic deformability of the electrically conductive material, a frictional connection is produced which produces a good mechanical and electrically conductive contact between the edge sections (contact sections) of the first electrodes and the electrically conductive material. The same applies to the edge sections (contact sections) of the second electrodes and the electrically conductive material introduced between adjacent second electrodes.Expediently, the electrically conductive material, in particular during the production process, is present as a metal paste which can be plastically deformed.The electrically conductive material preferably has a composition which, during the production method, makes it possible to produce a material bond to the carrier material of the carrier layers of the first and second electrodes. For this purpose, the electrically conductive material can be flowable, and in particular liquid, viscous or pasty, for example at the processing temperature. The electrically conductive material can also be melted by supplying heat during the production method in order to become flowable and in order to be able to form a mechanical and electrically conductive connection, in particular a cohesive connection, with the carrier materials of the carrier layers of the first and second electrodes.The electrically conductive material is preferably a metal from the group comprising silver, gold, aluminum and lead and mixtures or alloys of these metals. Further suitable materials which, on the one hand, are plastically deformable and, on the other hand, have a sufficiently good electrical conductivity are, for example. Graphite, graphene or polyaniline. The electrically conductive material is particularly preferably a solder, in particular a solder material which contains lead, tin or a tin alloy, zinc or copper or an alloy of these materials.The electrically conductive material preferably extends in the edge region (edge section) over the entire height in the stacking direction (or in the radial direction) between the adjacent first electrodes, i.e. between a lower first electrode and a first electrode arranged above it, so that the edge section of the carrier layer of the lower first electrode and the edge section of the carrier layer of the first electrode arranged above it are electrically contacted to one another via the electrically conductive material. The same applies to the second electrodes. In a lateral direction (i.e. in a direction perpendicular to the stacking direction), the electrically conductive material preferably extends over the entire length (in its longitudinal direction) of the respective edge section (contact section) of the first and second electrodes.In a transverse direction (i.e. in a direction perpendicular to the stacking direction and perpendicular to the longitudinal direction of the edge sections), the electrically conductive material preferably does not extend as far as the edge of the laterally adjacent electrodes of the respective other polarity. Short circuits can thereby be prevented, because a free, electrically insulating intermediate space exists in the transverse direction between the electrically conductive material and the electrodes (of the respective other polarity) laterally adjacent thereto.Particularly advantageous in the production of the electrode arrangement according to the invention is a secure contacting of the electrodes, in particular of the edge sections of the carrier layers serving as contact sections, and a better heat transfer in these edge sections. This is ensured by the invention by the stable mechanical and electrically conductive connection of the edge sections of superposed first electrodes and the edge sections of superposed second electrodes to the electrically conductive material.The production method according to the invention for producing an electrode arrangement for a battery cell, in particular for a lithium-ion battery cell, comprises the following steps:• Providing at least a first electrode, a second electrode, an electrically insulating first separator and an electrically insulating second separator, wherein the first electrode and the second electrode each comprise an electrically conductive carrier layer and a coating of an active material on at least one side of the carrier layer, and an edge section of each carrier layer is formed as a contact section which is at least partially free of the coating,• Forming at least one electrode assembly by stacking or overlaying the first electrode, the first separator, the second electrode, and the second separator, wherein the contact portion of the first electrode on a first side of the electrode assembly protrudes over the two separators and the second electrode, and the contact portion of the second electrode on a second side of the electrode assembly protrudes over the two separators and the first electrode.According to the invention, an electrically conductive material is applied to the contact sections of the first electrode and the second electrode when producing the or each electrode arrangement.In a first variant of the production method, the first electrode, the first separator, the second electrode and the second separator of each electrode arrangement are stacked along a stacking direction to form an electrode stack, wherein a plurality of such electrode arrangements can also be stacked on one another in the stacking direction.In this first variant of the production method, the contact sections of the first electrodes on the first side of the electrode arrangement, which are situated one above the other in the stacking direction, and the contact sections of the second electrodes on the second side of the electrode arrangement, which are situated one above the other in the stacking direction, are preferably arranged one above the other in alignment with one another in each case during the stacking of the plurality of electrode arrangements to form the electrode stack. In this case, the electrically conductive material comes to lie on the first side of the electrode arrangement between the contact sections of the first electrodes lying adjacent to one another in the stacking direction, and the contact sections of the first electrodes lying adjacent to one another in the stacking direction are electrically conductively contacted with one another. Accordingly, the electrically conductive material comes to lie in each case on the second side of the electrode arrangement between the contact portions of the second electrodes lying adjacent to one another in the stacking direction, and the contact portions of the second electrodes lying adjacent to one another in the stacking direction are electrically conductively contacted with one another.In a second variant of the production method, an electrode arrangement which comprises a first electrode, a first separator, a second electrode and a second separator is rolled up prismatically or cylindrically about a roller axis to form an electrode roller (so-called "jelly roll").In this second variant of the production method, the contact sections of the first electrode on the first side of the electrode arrangement and the contact sections of the second electrode on the second side of the electrode arrangement are preferably arranged one above the other aligned with one another in the direction of the roller axis when the one electrode arrangement is rolled up to form an electrode roller. In this case, the electrically conductive material comes to lie on the first side of the electrode arrangement between the contact sections of the first electrode of layers of the electrode roller lying one above the other in a radial direction, and the contact sections of the layers of the first electrode lying adjacent to one another in the radial direction are thereby electrically conductively contacted with one another. Accordingly, the electrically conductive material comes to lie in each case on the second side of the electrode arrangement between the contact sections of the second electrode of layers of the electrode roller lying one above the other in the radial direction, and the contact sections of the layers of the second electrode lying adjacent to one another in the radial direction are thereby electrically conductively contacted with one another.In a third variant of the production method, the separators are formed from a strip of an electrically insulating, bendable material by zig-zag folding of the strip about folded edges perpendicular to a stacking direction and are stacked to form a Z stack with successive layers of the separators. In this case, a first electrode and a second electrode are deposited alternately in the form of flat blanks between successive layers of the Z stack in the stacking direction, in order to form an electrode arrangement comprising a first electrode, a first separator, a second electrode and a second separator, which are each situated in alignment one above the other.In this third variant of the production method, preferably, when the first electrode and the second electrode are inserted between the successive layers of the separators of the Z stack, the contact sections of the first electrodes on the first side of the electrode arrangement, which are situated one above the other in the stacking direction, and the contact sections of the second electrodes on the second side of the electrode arrangement, which are situated one above the other in the stacking direction, are each arranged one above the other in alignment with one another. In this case, the electrically conductive material comes to lie on the first side of the electrode arrangement between the contact sections of the first electrodes lying adjacent to one another in the stacking direction, and as a result the contact sections of the first electrodes lying adjacent to one another in the stacking direction are electrically conductively contacted to one another. Accordingly, the electrically conductive material comes to lie in each case on the second side of the electrode arrangement between the contact portions of the second electrodes lying adjacent to one another in the stacking direction, and as a result the contact portions of the second electrodes lying adjacent to one another in the stacking direction are electrically conductively contacted to one another.The second side of the electrode arrangement is expediently situated opposite the first side of the electrode arrangement in all variants of the production method. This makes it possible to contact the first electrodes on a first side of the electrode arrangement via first connection elements which can be electrically conductively connected to the contact sections on this first side, while the second electrodes can be contacted by means of second connection elements in that the second connection elements are electrically conductively connected to the contact sections on the second side.For the production method, it is advantageous if the electrically conductive material is plastically deformable at the ambient temperature at which the production method is carried out. This ensures that the edge sections of the carrier layers of the first electrodes (for example the anodes) and of the second electrodes (for example the cathodes) can each be electrically conductively contacted with one another. Thus, it is possible in particular to fill the distance between a lower anode and an upper anode adjacent in the stacking direction completely with the electrically conductive material in order to produce a secure and permanent electrical contact between the lower and the upper anode. The same applies to the cathodes. In this case, in particular after the application of the electrically conductive material to a lower anode or a lower cathode, the applied quantity of the electrically conductive material can first be compressed in the stacking direction of the electrode arrangement and then an upper anode or an upper cathode can be applied, wherein the electrically conductive material expands due to its plastic elasticity and is pressed between the lower and the upper anode or cathode. In this way, a good and permanent electrical contact is produced between the lower and the upper anode and between the lower and the upper cathode, respectively.For the production method, it is furthermore advantageous if the electrically conductive material is flowable at temperatures above room temperature. If this is not already the case for material reasons, the electrically conductive material can be rendered flowable by addition of a solvent. A flowability of the electrically conductive material already present as a result of the material can also be improved by adding a solvent and / or by heating. If the conductive material is, for example, a solder which is solid in particular at room temperature, this can be rendered flowable by heating. A high flowability of the electrically conductive material enables simpler processing when carrying out the production method and ensures that the electrically conductive material connects well and flat to the edge sections of the first and second electrodes, respectively, whereby a good and permanent electrical contact between the first electrodes and a good electrical contact between the second electrodes can be achieved.Easy handling is achieved if the electrically conductive material is in the form of a flat band, the flat band being bent open in a C-shape before it is introduced between adjacent electrodes.The electrically conductive material is initially in the form of a flat strip or wire which is rolled on when applied to the contact portions of the first electrode and the contact portions of the second electrode. This ensures good, flat contacting of the electrically conductive material with the surface of the carrier layer of the first electrodes (for example the anodes) or of the second electrodes (for example the cathodes), so that a permanently good, firm and secure electrical contacting of the first and the second electrodes is produced.The electrode arrangement can be produced, for example, in the form of an electrode roll (so-called "jelly roll"), an arrangement stacked in a Z-shape ("Z-following") or an electrode stack ("stack"), in that a plurality of layers of the electrodes and of the separators are alternately stacked one on the other or stacked in a Z-shape or are rolled up to form an electrode roll. To produce the electrodes, a coating of an active material, for example of graphite or lithium iron phosphate or of comparable electrode materials, is first applied to a thin carrier layer, for example a copper or aluminum foil. The coating can be carried out here by the wet or dry method ("wet coating", "dry coating") on the carrier layer and can be compacted by a subsequent calendering process. The carrier layers with the applied active material are then cut to the required format and rolled up, folded or stacked with a separator film in each case lying therebetween. When coating the carrier layers with the active material, edge portions of the carrier layers are left free of the coating of the active material. These edge sections of the carrier layers free of the active material form contact sections at which the electrodes are subsequently electrically conductively connected to one another.As a result, the carrier layers (i.e. for example the copper and / or aluminum sheets or the copper and / or aluminum foils) form, on opposite edges of the electrode arrangement, in each case an edge section with a protrusion which is used for contacting. As a result of the layer structure of the electrodes and separators, an intermediate space is formed in each case between the projections lying one above the other, which intermediate space is filled with the electrically conductive material according to the invention in order to connect the electrodes and in particular the edge sections of the carrier layers to one another in an electrically conductive manner. The protruding sheet metal or foil regions (edge sections of the carrier layers) can then be bent such that continuous contacting is produced or made possible.In the method according to the invention, therefore, during the stacking of the electrodes and the separators, the electrically conductive material in the edge section of the electrode arrangement is introduced into the intermediate space between adjacent electrodes. In this case, this intermediate space is preferably completely filled with the electrically conductive material at least in the stacking direction (in the case of a stacked electrode arrangement) or in the radial direction (in the case of a rolled-up electrode arrangement), with the result that planar, continuous contacting of the first electrodes (for example of the anodes) and of the second electrodes (for example of the cathodes) is made possible without further deformation of the protruding edge sections of the carrier layers (sheets or foils) or is already produced completely or partially by the electrically conductive material introduced.The electrically conductive material can be provided in a solid or pasty form.The introduced electrically conductive material expediently already has sufficient compressibility or it is ensured by a calibration process before being stacked on top of one another that the thickness of the applied electrically conductive material completely fills the intermediate space at least in the stacking direction in the case of an electrode stack or in the radial direction in the case of an electrode roll without impairing the winding, folding or stacking process.Because the electrically conductive material is solid or paste-like, the introduction of the electrically conductive material during the production process of the electrode arrangements and in particular during the process of stacking the electrodes and the separators by rolling, folding or stacking at a corresponding point in the intermediate space between adjacent first electrodes (for example. Anodes) and between adjacent second electrodes (for example. Cathodes) are facilitated.It is particularly advantageous for the method according to the invention that the expansions of the edge regions (protrusions of the carrier layers which are free from the coating of the active material) can be minimized, in particular in a direction perpendicular to the stacking direction (in the case of an electrode stack) or in the axial direction (in the case of an electrode roll), in particular in comparison with the known methods for contacting the electrodes of an electrode arrangement, in which laterally protruding strip elements (so-called "tabs") are used and are electrically contacted to one another, for example, by soldering or by means of clamping elements (as in DE 10 2022 103 728 B3, for example). In the method according to the invention, therefore, less material is required for the carrier layers (sheets or foils) or more area is available for the coating of the carrier layers with the active materials. Likewise, the space requirement for contacting the electrodes within a battery cell can thereby be reduced, which enables a compact construction of the battery cells.These and further advantages and features of the invention and technical effects result from the exemplary embodiments explained in detail below with reference to the drawings. The following are shown: FIG. 1A : Schematic illustration of an exemplary embodiment of an electrode stack for a battery cell produced according to the invention; FIG. 1B : detailed view of a cross section of the electrode stack from FIG. 1A in the center of the electrode stack; FIG. 1C : Detailed illustration of a cross section of the electrode stack from FIG. 1A in the region of the edge section on a first side (a) of the electrode stack; FIG. 1D : Detailed illustration of a cross section of the electrode stack from FIG. 1A in the region of the edge section on a second side (b) of the electrode stack opposite the first side; FIG. 2 : Schematic illustration of a further exemplary embodiment of an electrode arrangement produced according to the invention in the form of an electrode roller, with a detailed illustration in cross section in a radial plane; FIG. 3 : Schematic cross-sectional illustration of a basic structure of an electrode arrangement which is produced in an intermediate step of the method according to the invention; FIG. 4 : Schematic illustration of the winding of a web-shaped electrode arrangement to form an electrode roll according to FIG. 2 ; FIG. 5 : Schematic illustration of the stacking of an electrode arrangement to form a Z stack.FIG. 1 shows a schematic illustration of a first embodiment of an electrode arrangement produced according to the invention in the form of an electrode stack S in a side view. The electrode stack S is composed of a plurality of first electrodes 1, a plurality of second electrodes 2, and a plurality of separators 7 stacked on each other in a stacking direction s toward the electrode stack S. The electrode stack S has a first side a (right side in the illustration of FIG. 1A ) and a second side b (left side in the illustration of FIG. 1A ). The first side a and the second side b of the electrode stack S each contain an edge section which serves as a contact section 5 for the electrical contacting of the first electrodes 1 and the second electrodes 2. The contact section 5- 1 on the first side a is electrically conductively connected to a first connection element 8- 1. Accordingly, the contact section 5- 2 on the second side b is electrically conductively connected to a second connection element 8- 2. Via the connection elements 8- 1 and 8- 2, an electric current can be conducted from the electrode stack S to a load (during the discharge of the battery cell) or from a current source to the electrode stack S (during the charging of the battery cell).To illustrate the structure of the electrode stack S comprising the first electrodes 1, the second electrodes 2 and the separators 7 arranged between the first electrodes 1 and the second electrodes 2, the central region of the electrode stack S denoted by "FIG. 1B" in FIG. 1B is shown in detail in a cross-sectional illustration. As shown in FIG. 1B, the electrode stack S includes a plurality of first electrodes 1 and a plurality of second electrodes 2, and separators 7 each disposed between a first electrode 1 and a second electrode 2 to electrically isolate the first electrodes 1 from the second electrodes 2.The sequence of electrodes 1, 2 and separators 7 arranged therebetween in the stacking direction s is shown in the detailed illustration of FIG. 1B in that the electrodes 1, 2 following one another in the stacking direction s are denoted by increasing reference numerals 1- 1, 1- 2, 1- 3, u.s.w. and 2- 1, 2- 2, 2- 3, u.s.w. and the separators arranged therebetween are denoted by increasing reference numerals 7- 1, 7- 2, u.s.w. respectively.The first electrodes 1 comprise an electrically conductive carrier layer 3, 3- 1, which is coated on both sides with a coating 4 made of an active material. In a corresponding manner, each of the second electrodes 2 likewise contains a carrier layer 3, 3-2, which is likewise coated on both sides with a coating 4 made of an active material. The materials of the carrier layer 3- 1 of the first electrodes 1 and of the carrier layer 3- 2 of the second electrodes 2 can be the same or different. In an electrode arrangement for a lithium-ion battery cell, for example, the first electrodes 1 can be designed as anodes and have a carrier layer 3- 1 made of a copper foil. The second electrodes 2 can be configured as a cathode and have a carrier layer 3- 2 made of an aluminum foil. The coating 4 of the first electrodes 1 (anodes) can be a graphite coating and the coating 4 of the second electrodes (cathodes) can be a coating of lithium iron phosphate or a coating of nickel cobalt oxide. A separator 7 made of an electrically insulating material is arranged between a first electrode 1 (anode) and a second electrode 2 (cathode). The separators 7 can each be made of the same electrically insulating material. However, it is also possible to use different separators 7- 1, 7- 2 made of different materials. The separators 7; 7-1, 7-2 isolate a first electrode 1 (anode) from an adjacent second electrode 2 (cathode), thereby preventing short circuit.In FIGS. 1C and 1D, the lateral edge portions of the electrode stack S on the first side a (FIG. 1C ) and on the second side b (FIG. 1D ) are illustrated in detail. It can be seen from FIGS. 1C and 1D that the carrier layers 3- 1 of the first electrodes 1 and the carrier layers 3- 2 of the second electrodes 2 are each free of the coating 4 of the active material in an outer edge section. These edge sections of the carrier layers 3; 3-1, 3-2 which are free of the coating 4 each form a contact section 5; 5-1, 5-2. In FIG. 1C, the contact portion 5- 1 of the first electrodes 1 is illustrated, and in FIG. 1D, the contact portion 5- 2 of the second electrodes 2 is illustrated. In the region of the contact portions 5; 5- 1, 5- 2, the support layers 3; 3- 1, 3- 2 form a lateral protrusion (in a transverse direction q) by the lateral edge portions 3- 1 of the first electrodes 1 on the first side a protruding above the second electrodes 2 and above the separators 7 (FIG. 1C ). Accordingly, the lateral edge portions of the support layer 3- 2 of the second electrodes 2 protrude on the second side b (in the transverse direction q) above the first electrodes 1 and above the separators 7. Between successive first electrodes 1 in the stacking direction s, an intermediate space is thereby created on the first side a (in the height direction). Accordingly, a space is created between successive second electrodes 2 in the stacking direction s on the second side b in the region of the edge section.According to the invention, these intermediate spaces between successive first electrodes 1 and between successive second electrodes 2 are filled at least partially and in particular completely in the stacking direction s by an electrically conductive material 6. In the examples shown in FIGS. 1C and 1D, an electrically conductive material 6- 1 is introduced on the first side a in the region of the edge section 5- 1 of the first electrodes 1. Accordingly, an electrically conductive material 6- 2 is introduced on the opposite side b between successive second electrodes 2 in the region of the edge section 5- 2. The electrically conductive material 6; 6- 1 electrically conductively connects the edge sections 5- 1 of the carrier layers 3- 1 of the first electrodes 1 to one another, such that the first electrodes 1 are electrically conductively connected to one another. Accordingly, the electrically conductive material 6- 2 electrically conductively connects the edge sections 5- 2 of the carrier layers 3- 2 of the second electrodes 2 to one another, such that the second electrodes 2 are electrically conductively connected to one another.To produce the electrode stack S shown in FIG. 1A, plate-shaped prefabricated first electrodes 1 and plate-shaped prefabricated second electrodes 2 are stacked one on top of the other to form the electrode stack S in the stacking direction s, wherein a separator 7 is introduced in each case between a first electrode 1 and an adjacent second electrode 2. The first electrodes 1, the second electrodes 2 and the separators 7 are each arranged plate-shaped and aligned with one another, so that a block-shaped electrode stack S is produced.In this case, in the region of the edge sections 5- 1, 5- 2 of the first electrodes 1 or of the second electrodes 2, the electrically conductive material 6- 1 or 6- 2 is applied to the edge sections 5- 1 or 5- 2 of the carrier layers 3- 1 or 3- 2 of the first electrodes 1 or of the second electrodes 2. The electrically conductive material 6- 1, 6- 2 is preferably plastically deformable and is placed in the form of a flat strip or a wire first of all on the edge section 5- 1 of a first electrode 1 and pressed, for example, with a stamp or a roller, so that a firm contact, preferably in the form of a materially bonded connection, with the surface of the carrier layer 3- 1 of this electrode 1 is produced. A separator 7 and a second electrode 2, a further separator 7 and subsequently a further first electrode 1 are then placed on top of it. In this case, the laterally projecting edge section 5- 1 of the further (upper) first electrode 1 lies on the upper side of the electrically conductive material 6- 1 and is expediently pressed, for example with a stamp or a roller, onto the electrically conductive material 6- 1 in order to produce a firm contact between the underside of the carrier layer 3- 1 and the upper side of the electrically conductive material 6- 1. Expediently, the electrically conductive material is flowable, so that a firm, in particular a cohesive connection between the electrically conductive material 6- 1 and the carrier layer 3- 1 can be achieved in the region of the edge section 5- 1 of the first electrodes 1. If a solder is used as the electrically conductive material, the electrically conductive material can be rendered flowable by raising the temperature to a temperature above the melting or flow point of the solder, as a result of which a firm and permanent, cohesive and electrically conductive connection can be produced between the electrically conductive material 6- 1 and the carrier layers 3- 1 in the region of the edge section 5- 1 of the first electrodes 1.The contacting of the second electrodes 2 takes place in a corresponding manner on the second side b of the electrode stack S during the described production of the electrode stack S. As can be seen from FIGS. 1C and 1D, the electrically conductive material 6- 1, 6- 2 does not extend in the lateral direction (counter to the transverse direction q, i.e. viewed towards the middle of the electrode stack) as far as the edges of the separators 7 or of the electrodes with a different polarity (second electrodes on the first side a or first electrodes on the second side b). This is advantageous in that short circuits are thereby avoided. If, for example, the electrically conductive material on the first side a would come into contact with the edges of the second electrodes 2, there is the risk of a short circuit between the first and the second electrodes. Therefore, a space is preferably present in the transverse direction q between the electrically conductive material 6- 1 and the edges of the second electrodes 2. In order to avoid unintentional short circuits during the production of the electrode stack S, it is therefore advantageous if the edges of the second electrodes 2 on the first side a are set back in the transverse direction q (i.e. inward toward the center of the electrode stack S) compared to the separators 7, as can be seen from FIG. 1C.The same applies to the electrically conductive material 6- 2 and the edges of the first electrodes 1 on the second side b, as can be seen from FIG. 1D.FIG. 2 shows a schematic illustration of a second embodiment of an electrode arrangement produced according to the invention in the form of an electrode target R in a perspective view and in the insert in a sectional illustration. The electrode roll R is composed of an electrode base structure in the form of an electrode arrangement A, comprising a first electrode 1, a first separator 7- 1, a second electrode 2 and a second separator 7- 2, as shown schematically in FIG. 3, wherein this electrode base structure is configured in the form of a web and is wound up to the electrode roll about a roll axis Ra. The winding process produces a layer structure, as is shown in a section in the sectional illustration in the insert at the bottom right in FIG. 2, with a sequence of the layers wound around the roller axis Ra, which comprise, for example, in the radial direction r a sequence of a first electrode 1, a separator 7, a second electrode 2, a further separator 7, a further first electrode 1 and a further separator 7, etc. The structure of each of the first electrodes 1 and the second electrodes 2 corresponds to the first exemplary embodiment of FIGS. 1A to 1D and is composed in each case of a carrier layer 3 (carrier layer 3- 1 for the first electrodes 1 and carrier layer 3- 2 for the second electrodes 2) and a coating 4 of an active material applied to both sides thereof.In FIG. 4, a method for producing the electrode roll R of FIG. 2 is schematically shown. In this case, the electrode base structure is first produced in the form of the electrode arrangement A shown in section in FIG. 3, wherein this electrode base structure is formed in the form of a web and comprises a first layer comprising a web of a first electrode 1, a second layer of a web of a separator 7 placed thereon, a third layer of a web of a second electrode 2 placed thereon and a fourth layer of a web of a further separator 7 placed thereon, as shown in FIG. 4. The tracks of the first electrode 1 and the tracks of the second electrode 2 each contain lateral edge sections which are free of the coating 4. These lateral edge portions serve as contact portions 5- 1 for contacting the first electrodes 1 and contact portions 5- 2 for electrically contacting the second electrodes 2, respectively. the sheets of the first electrode 1, the separators 7, and the second electrodes 2 are placed one on the other such that the lateral contact portions 5 protrude laterally, the lateral contact portion 5- 1 of the sheet of the first electrode 1 on the first side a protruding beyond the lateral edges of the second electrode 2 and the separators 7, and the lateral contact portion 5- 2 of the sheet of the second electrode 2 on the second side b protruding beyond the lateral edges of the first electrode 1 and the separators 7, as shown in FIG. 4.During the production of the tracks of the first electrode 1 and the second electrode 2, a strip of the electrically conductive material 6- 1, 6- 2 is applied in each case to the lateral contact section 5 of the respective electrode track (contact section 5- 1 of the first electrodes 1, contact section 5- 2 of the second electrode 2) along the entire track longitudinal direction L. The electrically conductive material 6; 6- 1, 6- 2 is present here as a flat strip or as a wire made of a conductive and elastically deformable material. The strip or the wire of the electrically conductive material can then be placed along the longitudinal direction of the strip on the respective lateral edge section of the first electrode 1 and of the second electrode 2, which forms the respective contact section 5- 1, 5- 2. In order to produce an electrically conductive and in particular a cohesive connection of the electrically conductive material 6; 6- 1, 6- 2 to the surface of the carrier layer 3- 1, 3- 2 of the first or second electrode, the electrically conductive material is preferably flowable and is pressed onto the respective lateral edge section of the carrier layer 3- 1 or 3- 2, for example by means of a calender (roll or press). In this case, the thickness of the electrically conductive material 6, 6- 1, 6- 2 in the radial direction r of the electrode roll R is adapted such that the electrically conductive material 6, 6- 1, 6- 2 extends at least to such an extent that the intermediate space between first electrodes 1 following one another in the radial direction or the intermediate space between second electrodes 2 following one another in the radial direction (i.e. in the height direction) is completely filled. In the transverse direction q (i.e. perpendicular to the longitudinal direction L of the web and parallel to the roller axis Ra), the electrically conductive material 6- 1, 6- 2 preferably does not extend as far as the edge of the laterally adjacent electrodes of the respective other polarity in order to prevent short circuits.During the final rolling up of the web-shaped electrode basic structure (electrode arrangement A according to FIG. 3 ) produced as described above about the roller axis Ra to form the electrode roller R, it is ensured in this case that electrical contact is produced between successive layers of the first electrode 1 in the region of the contact section 5- 1 on the first side a of the electrode roller R and between successive layers of the second electrode 2 in the region of the contact section 5- 2 on the second side b by the electrically conductive material 6, 6- 1, 6- 2. As a result, the individual layers of the first electrode 1 are electrically conductively contacted with one another and correspondingly the individual layers of the second electrode 2 are electrically conductively contacted with one another. It is advantageous if the electrically conductive material 6, 6- 1, 6- 2 is plastically deformable, since the material is pressed between the carrier layers 3- 1 of successive layers of the first electrode 1 and between the carrier layers 3- 2 of successive layers of the second electrode 2 during winding of the electrode roll R and thus ensures a secure mechanical and electrical contact.FIG. 5 schematically shows a method for producing an electrode arrangement in the form of a so-called "Z-following". Prefabricated, plate-shaped, in particular rectangular, blanks of first electrodes 1 and of second electrodes 2 are deposited between successive layers of separators 7, wherein the layers of separators 7 are produced by zig-zag folding of a separator web around folded edges K. The prefabricated blanks of the first electrodes 1 and the second electrodes 2 are produced as described above in the second embodiment (electrode roll R), with the difference that here plate-shaped (for example rectangular) blanks are produced instead of web-shaped electrodes. The blanks of the first electrodes 1 and of the second electrodes 2 each have edge sections on one side (i.e. on an edge of the plate-shaped blank) which are free of the coating 4 of the active material and serve as contact sections 5; 5- 1, 5- 1. As in the second embodiment, the edge contact portions 5- 1 of the first electrodes 1 and the edge contact portions 5- 2 of the second electrodes 2 are provided with the electrically conductive material 6; 6- 1 and 6- 2, respectively, over the entire length of the respective contact portion.During Z-following, a web or a strip of an electrically insulating material is folded as separator 7 in a zig-zag manner around parallel folded edges K and the folded layers of the separator web are deposited one on top of the other to form a Z-stack Z. When depositing the layers of the separator web, a first electrode 1 and a second electrode 2 are each alternately inserted between successive layers of the separator web, as shown schematically in FIG. 5. As a result, layers of the first electrodes 1, the separators 7 and the second electrodes 2 arranged one above the other in a stacking direction s are produced, and the contact portions 5- 1 of the first electrode 1 protrude on a first side a beyond the layers of the separator 7 and the edges of the second electrodes 2. Accordingly, the contact portions 5- 2 of the second electrode 2 protrude on a second side a beyond the layers of the separator 7 and the edges of the second electrodes 2. Preferably, the lateral edges of the second electrodes 2 are recessed inwardly with respect to the lateral edges of the separators 7 towards the center of the electrode arrangement, as is also the case with the electrode stack S of the first embodiment and can be seen in FIG. 5. The same applies to the contact sections 5- 2 of the second electrodes 2 on the second side b, which project there beyond the layers of the separator 7 and the edges of the inwardly set-back first electrodes 1.When the layers of the separator 7 are laid down in zig-zag form and the blanks of the first electrodes 1 and the second electrodes 2 are inserted, an electrically conductive contact is created between successive layers of the first electrodes 1 in each case in the region of the contact sections 5- 1 of the first electrodes 1, in that the electrically conductive material 6- 1 is pressed at the contact section 5- 1 between two successive layers of the first electrodes 1. The same applies to the contact sections 5- 2 of successive layers of the second electrodes 2, which are likewise electrically conductively connected to one another by the electrically conductive material 6- 2.In order to produce a battery cell from one of the electrode arrangements A which can be produced according to the embodiments described above, the contact sections 5- 1 of the first electrodes 1 are electrically conductively connected to a first connection element 8- 1 and the contact sections 5- 2 of the second electrodes 2 are electrically conductively connected to a second connection element 8- 2, as shown in FIG. 1A. This arrangement can then be inserted into a housing of a battery cell, wherein the connection elements 8- 1 and 8- 2 are conductively connected to connections arranged outside the housing and electrically insulated with respect to the housing. An electrolyte is introduced into the housing in order to allow ion flow during operation of the battery cell.List of reference charactersA electrode assembly a first side of the electrode assembly b second side of the electrode assembly S electrode stack Ra roller axis r radial direction s stack direction Z Stack 1 first electrodes 1- 1, 1- 2, 1- 3 individual first electrodes 2 second electrodes 2- 1, 2- 2, 2- 3 individual second electrodes 3 carrier layer 3- 1, carrier layer of a first electrode 3- 2 carrier layer of a second electrode 4 coating of active material 5 contact sections 5- 1, contact sections of the first electrodes 5- 2 contact sections of the second electrodes 6 electrically conductive material 6- 1 electrically conductive material applied to a contact section of a first electrode 6- 2 electrically conductive material applied to a contact section of a first electrode 7 separators 7- 1 first separator 7- 2 second separator 8- 1 first connection element 8- 2 second connection element

Claims

Method for producing an electrode arrangement (A) for a battery cell, in particular for a lithium-ion battery cell, having the following steps: • providing at least one first electrode (1), a second electrode (2), an electrically insulating first separator (7-1) and an electrically insulating second separator (7-2), wherein the first electrode (1) and the second electrode (2) each comprise an electrically conductive carrier layer (3) and, on at least one side of the carrier layer (3), a coating (4) made of an active material and an edge section of each carrier layer (3) is formed as a contact section (5; 5-1, 5-2) which is at least partially free from the coating (4), • producing at least one electrode arrangement (A) by stacking or stacking the first electrode (1), the first separator (7-1), the second electrode (2) and the second separator (7-2) one on top of the other, wherein the contact portion (5-1) of the first electrode (1) protrudes on a first side (a) of the electrode arrangement (A) over the two separators (7-1, 7-2) and the second electrode (2), and the contact portion (5-2) of the second electrode (2) protrudes on a second side (b) of the electrode arrangement (A) over the two separators (7-1, 7-2) and the first electrode (1), characterized in that, when producing the at least one electrode arrangement (A) or each electrode arrangement (A) on the contact portions (5-1, 5-2) of the first electrode (1) and the second electrode (2), an electrically conductive material (6; in each case; 6-1, 6-2), wherein the electrically conductive material (6-1, 6-2) is a wire or a flat strip, and the wire or the flat strip is rolled on the contact portions (5-1, 5-2) of the first electrode (1) and the second electrode (2) during the application.Method according to Claim 1, characterized in that a plurality of electrode arrangements (A) are stacked to form an electrode stack (S) along a stacking direction (s).Method according to Claim 2, characterized in that a web-shaped electrode arrangement (A) is rolled up prismatically or cylindrically about a roller axis (Ra) to form an electrode roller (R).Method according to Claim 1, characterized in that the separators (7; 7-1, 7-2) are formed from a strip of an electrically insulating, bendable material by zig-zag folding of the strip about folded edges (K) perpendicular to a stacking direction (r) and are stacked to form a Z stack (Z) with successive layers of the separators (7; 7-1, 7-2), wherein a first electrode (1) and a second electrode (2) are deposited alternately in the form of flat blanks between layers of the separators (7; 7-1, 7-2) of the Z stack (Z) which are successive in the stacking direction (r).Method according to Claim 2, wherein, when the plurality of electrode arrangements (A) are stacked to form the electrode stack (S), the contact sections (5-1) of the first electrodes (1) lying one above the other in the stacking direction (s) are arranged one above the other on the first side (a) of the electrode arrangement (A) and the contact sections (5-2) of the second electrodes (2) lying one above the other in the stacking direction (s) are arranged one above the other in alignment with one another on the second side (b) of the electrode arrangement (A), wherein the electrically conductive material (6-1) in each case comes to lie between the contact sections (5-1) of the first electrodes (1) lying adjacent to one another in the stacking direction (s) and the contact sections (5-1) of the first electrodes (1) lying adjacent to one another in the stacking direction (s) make electrical contact with one another, and on the second side (b) of the electrode arrangement (A), the electrically conductive material (6-2) comes to lie in each case between the contact sections (5-2) of the second electrodes (2) lying adjacent to one another in the stacking direction (s), and the contact sections (5-2) of the second electrodes (2) lying adjacent to one another in the stacking direction (s) make electrically conductive contact with one another.Method according to Claim 3, wherein, when the one electrode arrangement (A) is rolled up to form an electrode roll (R), the contact sections (5-1) of the first electrode (1) on the first side (a) of the electrode arrangement (A) and the contact sections (5-2) of the second electrode (2) on the second side (b) of the electrode arrangement (A) are each arranged one above the other in alignment with one another in the direction of the roll axis (Ra), wherein, on the first side (a) of the electrode arrangement (A), the electrically conductive material (6-1, in each case, is arranged between the contact sections (5-1) of the first electrode (1) of layers of the electrode roll (R) which are arranged one above the other in a radial direction (r), 6-2) and the contact sections (5-1) of the layers of the first electrode (1) lying adjacent to one another in the radial direction (r) come to be in electrically conductive contact with one another, and on the second side (b) of the electrode arrangement (A) between the contact sections (5-2) of the second electrode (2) of layers of the electrode roll (R) lying above one another in a radial direction (r) the electrically conductive material (6-1, 6-2) comes to be in each case lying and the contact sections (5-2) of the layers of the second electrode (2) lying adjacent to one another in the radial direction (r) come to be in electrically conductive contact with one another.Method according to Claim 4, wherein, when the first electrode (1) and the second electrode (2) are inserted between the successive layers of the separators (7-1, 7-2) of the Z stack (Z), the contact sections (5-1) of the first electrodes (1) lying one above the other in the stacking direction (s) are arranged one above the other on the first side (a) of the electrode arrangement (A) and the contact sections (5-2) of the second electrodes (2) lying one above the other in the stacking direction (s) are arranged one above the other on the second side (b) of the electrode arrangement (A) in each case in alignment with one another, wherein the electrically conductive material (6-1) comes to lie in each case on the first side (a) of the electrode arrangement (A) between the contact portions (5-1) of the first electrodes (1) lying adjacent to one another in the stacking direction (s) and the contact portions (5-1) of the first electrodes (1) lying adjacent to one another in the stacking direction (s) make electrical contact with one another, and the electrically conductive material (6-2) comes to lie in each case between the contact portions (5-2) of the second electrodes (2) lying adjacent to one another in the stacking direction (s) on the second side (b) of the electrode arrangement (A) and the contact portions (5-2) of the second electrodes (2) lying adjacent to one another in the stacking direction (s) make electrical contact with one another.The method according to any one of claims 1 to 7, wherein the second side (b) of the electrode assembly (A) is opposite the first side (a) of the electrode assembly (A).Method according to one of Claims 1 to 8, characterized in that the electrically conductive material (6-1, 6-2) is flowable at temperatures above room temperature and / or is rendered flowable by addition of a solvent.Method according to Claim 1, characterized in that an electrically insulating separator (7; 7-1, 7-2) is arranged in each case between an electrode (1-1, 1-2, 1-3) of the plurality of first electrodes (1) and a second electrode (2-1, 2-2, 2-3) of the plurality of second electrodes (2) which is adjacent thereto in the electrode stack (S).Method according to claim 1 or 10, characterised in that the carrier layer (3-1) of the first electrodes (1) and the carrier layer (3-2) of the second electrodes (2) are formed from a different carrier material and that the electrically conductive material (6-1) introduced between adjacent first electrodes (1) is the same or different from the carrier material of the first electrodes (1) and / or that the electrically conductive material (6-2) introduced between adjacent second electrodes (2) is the same or different from the carrier material of the second electrodes (2).Method according to one of the preceding claims, characterized in that the carrier layer (3-1) of the first electrodes (1) is made of copper and / or in that the carrier layer (3-2) of the second electrodes (2) is made of aluminium.Method according to one of the preceding claims, characterized in that the electrically conductive material (6; 6-1, 6-2) is a plastically deformable material.Method according to one of the preceding claims, characterized in that the electrically conductive material (6; 6-1, 6-2) is plastically deformable and has an elongation at break of more than 45% and an elastic modulus of less than 80 GPa.Method according to one of the preceding claims, characterized in that the contact sections (5-1) of the first electrodes (1) are electrically conductively connected to a first connection element (8-1) and the contact sections (5-2) of the second electrodes (2) are electrically conductively connected to a second connection element (8-2).Method according to one of the preceding claims, characterized in that the electrically conductive material (6; 6-1, 6-2) is a solder material, in particular tin or a tin alloy, graphite, graphene, polyaniline or a metal from the group silver, gold, aluminum, lead or copper or a mixture or alloy of these metals.

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